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Publisher/Editor: H. D. Cheek, Sr. aka 'Dr. Hioortortis ' 

V1N5: Hay-June, 1991 

A Journal of VHF-UHF Scanner Technology 4 Engineering 

Mshed at; COMMtronics Enqinseringi PQ BOX 262478; San Diego. Cft 92196 Copyright (c) 1991 <ftll Rights Reserved) $4,00 


Remember, we publish ten times a year so this issue marks 
the half-way point for 1 991 , and is more or less combined 
with June as a single issue. You won’t get a June issue, 
specifically. The same thing will happen at the end of 
the year when November and December are combined. 


Check the ’’Expire Date” in the upper right corner of your 
mail label. If it says ’’May 91”, then your subscription 
will expire with this issue. You can renew any time to 
take up where this issue leaves off. If your budget is 
tight for this month, drop a line saying so, and we’ll go 
ahead and send the July issue on time and trust that you 
will renew before the August issue comes out. If you 
don’t plan to renew, drop a note to briefly say why not 
and we’ll send you the July issue anyway just to express 
our appreciation of your patronage. Fair enough? 


Then do so right away so we can lay plans for the next 
r. You can take advantage of decent discounts and 
lcnewing for one full year, or even two for the maximum. 
Rates are unchanged at $15/6-mos; $25/yr or $45/2-yr. We 
are growing and we’re getting better. Please come along! 


Actually, it’s not new; we’ve had it all along. It’s 

just that this particular printer is about as slow as 

molasses flowing through a straw in the winter. That’s 
not the only reason it has not been used before? this 
print is about 12$ larger, which means a 12$ reduction in 
the amount of information. In the past, I felt you might 
prefer more info at the expense of a less neat typestyle. 
There have been several justifiable complaints, however, 
so I’ll try this style of print on you and see how you 
like it. Your feedback will be appreciated and it might 

even influence the decision on whether or not we stick 

with it. Is it a good tradeoff? Please tell me! 


Three technical errors have emerged in Vol-2 of the SMH 
so far. Please make corrections in your copy of the book 
as follows: Page 58; Step 7.B: Change ”IC-5, Pin 10” to 

Pin 12”. Then turn to page 83; MOD-5, Step C: 
nge ’’Pin 3 of IC-6” to ’’Pin 6 of IC-6”. Then, in the 
next sentence, change "PR0-2004” to ’’PR0-2005”. That’s 
all the glitches so far other than ignorant typos. Sorry 
for any inconveniences this stupidity may have caused. 

This has been a back burner project of mine for over a 
year now, and I just haven’t gotten around to working out 
the details. Recently, a reader sent me info about an 
article in the May-1990, issue of POPULAR ELECTRONICS 
MAGAZINE, titled ’’Add CW & SSB To Any Shortwave Receiver” 
by Michael Covington. The circuit is super simple and I 
hoped it might do the trick. Maybe not, because I tried 
it six different ways and it failed to work. Maybe I am 
overlooking something. Have any of you tried it? The 
principle seems sound but I’m missing out on something. 
I’ll be glad to send the info to anyone who would be 
interested in brewing up this little circuit and report 
the results back to me. If you want the info, send me a 
SASE and one loose extra stamp. The principle of this 
circuit makes it a credible candidate for SSB detection 
in the PR0-2004/5/6 scanners and other scanners which 
have the AM mode and 25-30 MHz coverage. 

Just understand that SSB on 30 MHz and up is practically 
non-existent though apparently the new Land Mobile band, 
222-225 MHz has been authorized for Amplitude Compandored 
Sideband (ACSB). United Parcel Service was planning to 
set up a nationwide dispatch/shipment tracking system on 
this band using ACSB but I hear that it has been either 
delayed or shelved for the time being. Maybe in time, 
we’ll see some SSB activity on VHF & UHF. For now, the 
only SSB of significance is between 27-30 MHz; CB’ers, 
Freebanders and Hams operate SSB in that range. There 
may also be a few survivalist groups operating with SSB 
between 25.5 MHz and 26.5 MHz. 


Most of my modifications and electronic projects are 
designed around the Radio Shack catalog because it is 
such a universal reference book and it’s best that we all 
play to the same ’’sheet of music”, so to speak. Alas, 
Radio Shack steps to the beat of its own drummer and does 
not carry many things needed by the electronic hobbyist. 
liJe have to turn to outside sources for the more critical 
chips, parts and supplies for our modifications. By and 
large, you’re referred to ’’your local electronics supply 
house” in my books and here in the ”ti)SR". Come to find 
out that many readers just don’t know where else to turn 
if Radio Shack can’t meet their needs. Relax now! 

DIGI-KEY CQRP, a large mail-order electronic supply firm 
puts Radio Shack to shame in the parts department and the 
prices are hard to beat! Digi-Key claims to ship 99$ of 
all orders within 24-hours, also hard to beat. Get on 
their mailing list for a great catalog which is issued 
every 2-months. Write or call as follows: 

Digi-Key Corporation; PO Box 677; Thief River Falls, MINN 
56701-0677, or call (BOO) 344-4539. Digi-Key has an 
extensive inventory of small electronic parts, including 
chips of all brands & kinds, transistors, resistors, 
capacitors, coils, chokes, resonators, crystals, LEDs and 
relays. Digi-Key also has a good stock of electronic 
tools and test equipment. And they deal in nickels and 
dimes as well as in bucks! Definitely hobbyist oriented! 


Public Message (Sent) 

Message ff 9136 ^SHORT-WAVE* 

To : Paul Scalzo 

From : John Mccolman 
Subject : Re: AR-3000 RECEIVER 
Date : 91/04/08 1::3:00 

I ! ve been satisfied with the sensitivity of the AR-3000, 
not overwhelmed, but definitely satisfied. The extra 
little features like for search (being able to lockout 
individual frequencies) makes the radio unique. It is 
not as fast as I’d hoped, but I like it overall. 


* Origin: ANARC BBS-Assoc.of North American Radio Clubs 
(913)345-1978 (280/3) 

Message #8443 - SHORTWAVE 

From : Dan Morisseau on (1:202/701) 

To : Chris Conner on (1:202/719) 

Subject : A0R AR-2500 
Date : 14-Apr-91 22:23 

CC> I am interested in purchasing a continuous coverage 
CC> scanner and I am considering the AR-2500. Can anyone 
CC> who has had some experience with this particular 
CC> model please let me know how you liked/disliked it. 

Chris - I owned a 2500 for about 25 days and felt obliged 
to return it to ACE for the promised refund. It was 
extremely plagued by images from commercial FM broadcast 
throughout the VHF-Hi band and was just plain impossible 
to use on VHF-Lo because of birdies. I tried a number of 
’’fixes” suggested by ACE, including an FM trap from Radio 
Shack and a higher output power supply. Nothing worked to 
any degree of satisfaction. It WOULD work on UHF freqs IF 
the attenuator was switched in. Performance on freqs 
below 30 mHz was not fully explored, but from what little 
I did play around, it seemed to be worse than VHF. In 
short, Chris, I would not recommend this unit to anyone, 
based on my experience. I have since taken the money I 
put in the AR2500 (and more) and invested in an IC0M 
R-7000. I am more than satisfied that I got my moneys 
worth there. Suggest that you save yourself a great deal 
of inconvenience and disappointment and search for 
another radio. As I said above, the ICQM R-7000 is a lot 
more expensive, but it is a lot more radio, too. 

* Origin: The Boardwalk! * Master Series Support * 

206-941-3124 (1:343/47) [EDITOR’S NOTE: This message was 
edited for brevity.] 


I haven’t actually done the cellular restoration mod, but 
thanks to Larry Rosen who sent me a copy of the Service 
Manual for the TS-2, I was able to determine a prob 
best course of action. Remove the top cover and examine 
the top-right-front area of the receiver behind the front 
panel and locate the ’’Processor PCB Assy”. There will be 
a large 40-pin IC chip, U-502, to capture your immediate 
and exclusive interest. Find Pin 40 and nearby resistor, 
R-512. Examine the board, front or back, between R-512 
and Pin 40 and note where Pin 40 is jumpered or wired to 
ground. Remove or clip that ground to restore cellular 
capability. BEWARE that intercepting cellular phone 
calls is a violation of the ECPA. A review of the TS-2 
Manual suggests several other possibilities for mods: 

(1) A standard 16-pin NFM chip is used, so refer to VI N4, 
page 6 and associated articles for hints in this area. 

(2) A speedup might be achieved by replacing Y-501 , a 
4.19 MHz crystal with something 50-100? higher in freq. 

(3) SW Interface (MOD-14); Extend Delay (MOD-29); Event 
Counter (MOD-30); CTCSS (MOD-31); Carrier-On Indicator 
(MOD-32); and the Auto Tape Recorder Switch (MOD-33) all 
should be possible to do on this rig. (4) TAPE RECORDER 
output is probable by tapping the high side of the Volume 
Control via a 0.1 -uF capacitor. Use shielded mic cable 
to the new jack if you install one. (5) S-metering is 
probably not feasible in this unit. (6) Extra memory 
channels and recovery of other freqs also not probable 

MOD-30 Event Counter Note 

A slick little mod that’s easy to do and can be most 
useful not only with your scanner but perhaps in other 
areas limited only by your imagination. The Counter 
Module requires a ”AA” flashlight battery for operation. 
If you’re like me, your first instinct was something 
like, ”Aw, geez, not another battery to run down every 
few days”. Change ’’days” to years. I’ve had a cheap AA 
battery in my Event Counter for over six months now, and 
the terminal voltage still measures over 1.5-v. Moral : 
don’t bother with trying to feed external power to the 
module as I first considered. Just replace the battery 
every 6-12 months whether needed or not! 

PRJ-3 Snatch ’N Latch DTMF Decoder Note 

Vol-2 of my book discusses a super slick telephone dial 
tone decoder that can be used to decode dial tones that 
you hear over your scanner or dial tones from just about 
any source, including direct from the phone lines and 
from recordings made on tape. HB Technologies, 
developer, now has available an etched circuit bo, 
ready to stuff with a handful of components to complete 
the Snatch *N Latch project. They even supply the more 
difficult to obtain DTMF decoder chip, and perhaps other 


V1N5- Page 2 

parts* The availability of the printed circuit board 
makes this project a snap. Write to HB Technologies, PO 
Box 2771, Spring Valley, CA 91979 for more info. 

The Snatch ’N Latch DTMF Decoder board can be installed 
a small project box or even inside of most scanners. 
i ve built two so far, one that will fit into a pocket 
for portability and the other is attached to my PR0-2Q04 
TurboliJhopper scanner via a remote box and umbilical 
cable. A neat and sometime useful snoop gadget! 

The New Wish List; Item 4 

Electronic RF Attenuators may now be available that can 
be adapted to our scanners! Chris Storey of Los Angeles, 
CA, called my attention to a ,t TTL Controlled Attenuator" 
made by Mini-Circuits, Inc, PO Box 350166; Brooklyn, NY 
11235-0003; (718) 332-4661. The 50-ohm TOAT-series 

performs with 6-usec switching speed and handles power 
levels up to 1 -milliwatt. Several styles and packages 
are available, some that look like IC chips and others in 
a metal enclosure with connectors. Contact Mini-Circuits 
for more info. Suitability for scanners is not known at 
this time, but you can ask them! 

The New Wish List; Item 9 

I haven’t done the hypothetical "High Speed Electronic 
Antenna Switcher" discussed on pages 216-217 in Vol-2, 
but the idea still gnaws at me. Every now and again I 
w nk at the diagram on page 217, and an "error" jumped up 
me that 1*11 tell you about here. Refer to the right 
side of the drawing at the 8-pin connector. Notice where 
I have shown jumpers from Pins 1 & 2 and 3 & 4? Well, 
this would cause immediate problems if you tried to use 
two bands to control one antenna as shown. Instead of 
the jumpers as shown in Fig 5-1, we’ll use some isolation 
diodes, so refer to the corrected method below: 

Another change for the better that occurred to me to 
mention is to change the 1-k resistors to 2.2k, 2.7k, or 
even 3.3k to avoid loading down the front end circuit. 
The 470k resistor might be reduced to 220k, but it must 
remain a rather high value, certainly above 100k. Has 
anyone experimented with this circuit yet? 


3 one’s for you hams, CB’ers and Freebanders who use 
any of several transceivers of Uniden origin including 
the HR2510, HR2600, Realistic HTX-100 and the Lincoln 

export rigs. The UNIDEN COOKBOOK is a compilation of 
some 20 mods, tips, tricks and kinks on the above radios. 
Among this hot stuff are power increases, variable power 
controls, improvements in the noise blanker and audio 
circuits, and troubleshooting charts. Easy to read and 
comprehend, THE UNIDEN COOKBOOK is available from its 

author as follows: > Bud Stacey KC4HGH; P0 Box 907; 

Satsuma, AL 36572 < I don’t remember the price, so 

send Bud a SASE and an extra loose stamp for the details. 


I am a licensed ham, so the appeal of the IC0M 24/AT 
Handheld was too much to pass up. I spend lots more time 
scanning than hamming, so the idea of a scanner that also 
transmits (for highway emergencies or just socializing) 
was a bit too much to pass up. Of course, IC0M sells the 
24/AT as a ham radio that just happens to scan. The out- 
of-band receive/scan features are not emphasized. The 
24/AT scans 40 channels between 75 MHz and about 1 GHz. 
Operation of the unit side by side with a Bearcat 200 XLT 
on the VHF-Hi & UHF bands indicates that the sensitivity 
of the 24/AT is notably superior. In the B60 MHz range, 
I’d give the IC0M a slight edge. I won’t elaborate on 
the ham related features since that’s a bit beyond the 
scope of the "WSR" except to say it is an outstanding 
unit with exceptional performance. I will offer some 
comments to potential buyers of the 24/AT as a scanner: 

The scan speed is slow compared to the conventional 
Uniden/Realistic scanner. The priority channel cannot be 
used while you are scanning. When you turn the unit ON, 
it does not automatically resume scanning, you must 
manually initiate the scan function. There are bells and 
whistles, like signal strength display, auto turn on/off 
timers. Generally, all can be selected or deselected. 

The large number of keyboard selectable features often 
requires that more than one button on the small keyboard 
be pressed at once, so it is difficult to invoke these 
options while driving or walking. All in all, I give the 
24/AT very high marks, though it takes a little while to 
adjust to its complexity and peculiarities. 

By: D. L. Goodson; Orlando, FL 
[EDITOR’S COMMENT: One wonders if the 24/AT can be made 
to transmit out-of-band; some do, I understand....... /be] 


If you’re deaf in one ear and can’t hear out of the other 
like me, then you probably find lots of fault with the 
speaker that’s in your scanner. It’s cheap, funky and 
ineffectual unless you’re sitting right on top of it. I 
found a great all-purpose extension speaker some years 
ago that’s still available today. Radio Shack’s CB 
Extension Speaker, § 21-549 is a real performer for the 
tone deaf like me. What makes it so good, not to mention 
the compact case, nice mounting bracket and long cord, is 
the actual speaker element inside the case! It’s got a 


VI N5 - Page 3 

huge magnet on a sturdy frame quite similar to #40-1197 
replacement speaker. The bottom line is that it works 
very well for the intended purpose. 

Hobbyists sometimes go to unneeded extremes to fashion 
external speakers for the listening post. I’ve seen 
costly stereo speakers in use that didn’t sound any 
better than the scanner’s stock speaker. No wonder. The 
audio reproduction circuits in shortwave and scanner 
receivers are designed for the VOICE band of 300 Hz to 
3000 Hz and that’s all that the speaker will ever get.. 
It makes no sense, then, to go overboard. In fact, best 
is sometimes worse in this case. Fidelity is one thing 
and intelligibility can be quite another. Your home 
stereo requires fidelity but your listening post demands 
intelligibility! Communications receivers can produce 
distortion above and below the voice band which can be 
reproduced in a hi-fi speaker to muddle or diminish the 
needed intelligibility. It’s best to select a speaker 
precisely tailored for radio comm, and that means center 
performance at about 1.5 KHz with upper and lower cutoffs 
of about 3 KHz & 300 Hz, respectively. Radio Shack’s CB 
Extension speaker is eminently suited for this job. And, 
it’s very, very rugged; ideal for mobile, portable and 
most any other commo application. 


Right after Vol-1 of my Scanner Modification Handbook 
went to press, the FCC authorized additional channels for 
the CMT bands. This may or may not render obsolete the 
charts & tables in Vol-1, pages 64, 66, 68 & 69, because 
the new freqs are not in use in all areas yet. Cellular 
phone bands are listed below for your references 









Non-telephone Company 


844. 9B0 



Telephone Company 





Non-telephone Company 





Telephone Company 

869.01 C 




Non-telephone Company 





Telephone Company 





Non-telephone Company 





Telephone Company 

As you may know, cellular mobiles are not usually worth 
monitoring because of very short range and one-sided 
conversations. Incidentally, the mobile frequencies are 
always exactly 45.000 MHz below the base frequencies. So 
if you hear a cell site on 891.540, the mobile will be on 
846.540. NOTE: it is illegal to monitor cell mobiles and 
bases, but you knew that anyway. I just mention it again 
to keep from getting jailed for making you think it’s ok. 

Handheld scanners are pretty neat, but they’re used about 

90$ of the time in fixed locations, usually the listening 
post. It would be neater if they came with some of the 
frills, bells and whistles common to base scanners. But 
then handheld scanners sometimes need bells and whistles 
in portable operations, too. 0k, we will just have to 
the job for ourselves. ATTENTION PRIVATE DETECTIVES ^ 
LAW ENFORCEMENT PERSONNEL: The first two mods below may 
be eminently applicable to your needs! 

Tape Recorder Output Jack 

This one is easy. The ’’high" lug of the Volume Control 
carries just the right level of audio signal for most any 
tape recorder and it’s accessible. But where to put a 
jack? Remember, we have to keep the scanner maintainable 
and easy to disassemble, so we don’t want any jacks 
installed in the plastic case to complicate future access 
and maintenance. No sweat! First snag a pair of submini 
3/32" phone jacks, RS # 274-247 and a 0.1 -uF capacitor, RS 
#272-135 or 272-1069. That will be all you’ll need here. 
Save the spare 3/32" jack because you’ll need it below 
for the Automatic Tape Recorder Switch. 

Remove the back plastic case of the PRO-34 and lay it 
aside. Position the scanner so that you’re looking at 
the rear, exposed circuit board with controls up and 
battery compartment down. Now eyeball the area of the 

upper left corner where the Volume Control is and then 
downward an inch or so to T-102. That area between T-102 
and the Volume Control along the edge of the PCB is qu5*“' 
flat and unencumbered with parts. A perfect place 
super-glue one of the 3/32" phone jacks on its side with 
the plug opening pointing outward to the left side. Move 
the jack around a little first to make sure the scanner’s 
case can be reinstalled without touching the jack. In 
other words, the jack will be recessed from the side 
panel just a little and permanently affixed to the 
circuit board. No problem... the jack will never be a 
bother that way! When you see what I am talking about 
here, put a drop of super glue on the plastic side of the 
3/32" jack and press it to the PCB on the chosen spot. 
Again, be sure the jack opening is recessed in a little 
to permit the case to easily go on and off. 

Solder one lead of the 0.1 -uF capacitor to the high lug 
of the Volume control. One end lug of the Vol control is 
ground and has a BLACK wire, so the other end lug with 
the GREEN wire is the one where to solder the capacitor. 
Solder the other lead of the capacitor to the rear lug of 
the 3/32" jack that’s farthest from the ground lug. 
Solder the ground lug of the 3/32" jack to a nearby PCB 
ground trace. You may have to scrape some green lacquer 
off the ground trace first. When done, there will be an 
unconnected lug on the 3/32" jack, and that lug will be 
between the ground lug and the hot lug. 

Temporarily reinstall the rear case.... and mark where a 
hole will have to be in order to access the jack from 
outside. This is a trial & error operation mostly, and 


VI N5 - Page 4 

when you think you’ve got the spot, drill or melt a tiny 
hole through the side of the case to align with the jack 
opening. Then close the case to make sure your hole is 
on center with the jack. If not, make enlargements of 
that hole in the necessary direction to get it centered 
r the jack. Once you f re sure it’s centered, then 
drill it out to 3/8" diameter, to accommodate the plug 
that will be needed! That's it; you 1 re almost done now. 
Hake up a patch cord with shielded coax or mic cable to 
fit between this jack and your tape recorder. You can 
now record any signal that’s picked up by the PRO-34. 
Furthermore, the mod is self-contained and will never 
hinder future access to the innards of the scanner! 

Automatic Tape Recorder Switch For the PRO-34 

Tape recorder jacks on scanners are mostly worthless 
unless you’re right there, johnny on the spot, to operate 
the damn things all the time. A tape recorder output and 
my Automatic Tape Recorder Switch (ATRS) go together like 
kids and puppies, however. See Vol-1 , MOD-5 and Vol-2, 
MOD-33 for two varieties of ATRS. We will use MOD-33 in 
the PRO-34 by virtue of its simplicity and smaller size. 
Instead of building MOD-33 on a perf board as shown in 
V ol-2, we’ll have to build it component by component 
right into the PRO-34. Space in there is very limited, 
you see and we need to keep things condensed. But it's 
not difficult as you will see. 

The hardest part is the 3/32” jack required for the 
ate Control function output but it's no more difficult 
u<an the jack we installed just above for the Tape Rec 
Output. Remove the rear case of the PRO-34 again and 
scope out the left side of the exposed PCB. Find T-102 
again and then just down the board from it is a thing 
that looks like a quartz crystal, XF-101. Well, right 
there between T-102 and XF-101 is a prime spot for the 
3/32” Remote jack... almost. Try a fit and you’ll see 
that it’s tight. File the sides and lower corner edges 
of the 3/32" jack until the fit is perfect. It won’t 

take much. Taking the same precautions described above 

for the Tape Recorder Output jack, super-glue the Remote 
jack to the PCB so that the jack opening points outward 

to the side of the case but does not get in the way of 

opening and closing the case. Now put the rear case back 
on and mark a spot that centers over the opening of the 
3/32” Remote jack. When you’re sure it’s centered, drill 
out a 3/8" hole to accommodate a Remote patch cable. 

Use the diagram on page 188 in Vol-2 of my book, but 
three of tie parts will change. Instead of the relay 
called for there, use RS #275-232, a 5-v reed relay; it’s 
small with low current needs! R-1 and R-2 should be 
changed to a single 100-k resistor, RS #271-1347. Install 
the LED (D-2) to be visible as a "Carrier On Indicator" 
you want; it is necessary for the circuit but it 
Jn’t be visible unless you want. I installed my LED 
in a hole between the Volume and Squelch Controls! Now 
decide where to install the On-Off switch for the ATRS. 

I installed mine between the Antenna Connector and the 
Squelch Control. The RS micromini toggle switch #275-624 
is suitable but don’t use anything larger. 

Super-glue Q-1 , the 2N2222A switching transistor, upside 
down to the top of IC-101 on the PRO-34 ’s PCB. Solder 
one end of the 100-k resistor (new R-1) to Pin 13 of 
IC-101 and the other end to the base of Q-1. Solder the 
emitter of Q-1 to a nearby PCB ground spot. Physically 
lay the reed relay (pins up) in the uncongested area 
between C-205, TP-105 and C-216. It will kind of wedge 
in there without harm. Assuming that the LED and on/off 
switch are mechanically installed, complete the wiring of 
the relay, D-2 LED, S-1 , J-1 and D-1 in accordance with 
the diagram on page 188 in Vol-2, and that will do it! 
Be critical of your hookup wire; use wires salvaged from 
RS #278-776 or 278-775 and DON'T use their regular hookup 
wire if you know what’s good for you and your PRO-34. 

NOTE: Don’t ground any of the lugs on the 3/32" Remote 
jack to scanner ground. They should be connected only to 
the relay pins and nothing else. The ground lug of the 
Remote should be wired to one of the relay switch pins 
and the lug on the jack farthest from the ground lug will 
be wired to the other relay switch pin. The middle lug 
of the Remote Jack will not be connected. 

Speeding Up Scan and Search in the PRO-34 

This is well covered in MOD-38 in Vol-2 of my book, but I 
can add a little to it now. The best way to do this mod 
is to remove CX-1 , the original stock 2 MHz resonator. 
This is done by lifting the Logic/CPU Board up and out of 
the front case so you can access the bottom side of the 
PCB. Drats, but there’s a shield in right over the 
solder points of CX-1 and it will have to be desoldered 
in three places to be moved out of the way. A hassle, 
but worth the time and effort. Desolder CX-1 and remove 
it from the board. For warp drive, install a 7.37 MHz 
resonator salvaged from a speeded up PR0-2004 or 2005, or 
else order the 7.37 MHz resonator from Tandy National 
Parts in Ft. Worth, TX; (800) 442-2425. Ask for part # 
CST7.37MT from either the PR0-2004 or 2005. My PRO-34 
now races along at something like 33-ch/sec; of course 
the delay was reduced to about a half-second, but...!!! 
You can always go with something a bit more "reasonable" 
like 3 or 4 MHz. Radio Shack’s color burst crystal at 
3.58 MHz, #272-1310, has been reported to work well. 


There’s a lot of hype and hyperbole about speeding up the 
scan & search rates of scanners these days. There is 
also a danger of blowing up the expensive CPU chip if you 
get too carried away. Let me explain: CPU’s are little 
more than a container for a huge array of electronic 
"gates" or doorways. All CPU’s are driven by a clock 
oscillator for precise timing or synchronization of those 
gate openings and closures. The critical thing here is 


VI N5 - Page 5 

that every opening or closure requires a bit of current* 
When the clock oscillator is increased in frequency, then 
there are more gate operations per second, and therefore 
a higher current requirement per second. Well, current 
flow per second is a basic quantity of power... and one 
form of power is heat! And, heat destroys CPUs. So the 
faster you run them, the greater the current drain and 
there is a point where a failure will occur. Count on 
$40, minimum, if you replace the CPU yourself; and $100 & 
up if someone else has to do it. I can’t be sure of all 
the exact engineering limits of the CPUs in various 
scanners, but I am fairly certain that up to 10 MHz is 
safe in the PR0-2004 and 2005; 16 MHz for the PR0-2006; 
7.37 MHz for the PRO-34; 800 KHz for the Uniden BC-200/ 
205XLT, and that’s about all on which I can speak with 
any certainty. As a rule, SQ% speed ups appear fairly 
safe; any more than that without knowing for sure could 
lead to problems. I am quite confident that 18 MHz blew 
up a CPU in one PR0-2006 that I know of, though I have 
successfully used 18 MHz in a number of others. As a 
result of this suspicion, however, I will not take a 2006 
above 16 MHz anymore. Speeding up scanners is a lot like 
revving car engines. Use caution; there are limits! 

=-=- SPEEDING UP THE BC-200/205XLT & REGENCY R-4030 -=-= 

MQD-41 in Vol-2 of my Scanner Modification Handbook 
covers this pretty well, but at the time I didn’t know of 
a ready source for speed up resonators unless you were 
willing to buy a zillion from Murata-Erie which won’t 
sell you just one. Now I know where you can get just one 
and maybe a few other neat things besides. See page 2 of 
this issue for the address & phone number of Digi-Key 
Corp. They have Panasonic EF0-A80DK04B ceramic 800 KHz 
resonators for sale at less than a buck each. Digi-Key ’s 
part number is P-9947. An 800 KHz resonator will double 
the SCAN & SEARCH speeds of the BC-200/205XLT. Digi-Key 
also has slower resonators if you’d prefer milder speeds. 

By the way, *16% of ”WSR” readers own a BC-200/205XLT. 
How do I know? From the data on the subscription blank! 


After your base scanner has been operating for a while, 
put your hand on the top cover. Notice how warm it is? 
If as cool as a cucumber, then go on and find something 
else to read in this issue. If the case is any warmer 
than the surrounding air temperature, then this article 
is for you (and your scanner). 

A handheld scanner is great; stick in a battery pack and 
off you go; else power it from an AC-DC adaptor. Base 
scanners are great too; plug ’em into the wall where they 
stay and heat up. Heat accelerates the aging or metabolic 
rate of just about everything in the Universe, especially 
things electronic or electrical. Cooling or prevention 
of heat build-up will prolong the life of most electronic 
equipment, and your scanner is a composite example of the 

point I will be making here. Inside your scanner is a 
bit of practically everything, from crystal to oscillator 
to computer to RF and audio amplifier. All these circuits 
work best and last longer if operated at reasonably cool 
temperatures. Refrigeration not necessary; just rear 

Whenever electricity flows in a circuit, a bit of heat is 
generated from every device through which current flows. 
By and large, we can’t do^ny thing about that. Power (P) 
equals Current squared (I ) times resistance (R). So if 
two jjilliamps flow through a 1000 ohm resistor, then 
.002 x 1000 = .004 watts generated. Not much, but more 
or less current flows through lots of circuits with lots 
of components in your scanner, and each one releases a 
bit of heat into the air inside the case. Cumulatively 
this might add up to several watts which even in a closed 
space will not cause an inordinate rise in temperature. 
So why does the scanner’s case FEEL WARM, even hot? There 
is another source of heat that can be under your control! 
The transformer in the scanner’s power supply 

If your scanner is one like the BC-760/950XLT , then 
things are already under control since it does not have 
an internal power supply; it runs from an external AC-DC 
adaptor or other DC power source. But if you have a 
PRD-2004, 2005, 2006, or other base scanner with a cord 
that plugs into a 110-v wall socket, then you’ve already 
noticed how warm your scanner can get. And you can do 
something about that at relatively low cost. 

If yours is A/C powered, then all current that circular 

in your scanner has to pass through the power transformer 
first and that’s where a lot of that current is consumed 
and transformed into HEAT! That heat is radiated into 
the air space inside the scanner where it raises the 
temperature of everything; not just the case that you can 
feel! The ’’secret of scanner immortality” is to not use 
its internal power supply! 

The PR0-2004/5/6 and many other base scanners come with a 
DC power jack on the rear panel. This jack has a tiny 
switch in it which if the proper plug is inserted, will 
disconnect the internal A/C power supply and allow the 
scanner to operate from a source of external DC power! 
It is highly recommended that YOU power your scanner this 
way to minimize the heat accumulation inside the scanner, 
and make it run demonstrably cooler! So how to do it? 

All you need is a power supply or an AC-DC adaptor that 
will provide 10 to 16 volts and rated at about 500-ma 
(1/2 amp). Radio Shack has four models that will power 
the PR0-2004/5/6 or any of their base scanners: 22-120; 

22-127; 273-1653; 273-1652. The first three are a bit 
pricey because they’re designed to handle more than just 
a scanner, but the last one is priced right and it comes 
with the exact plug that you’ll need. Get the polar 
of the plug right with center (+) and outer shell (-) and 
you’ll be in business. After a while, notice how cool 
your scanner runs and then feel the AC-DC adaptor... it 


\I 1N5 - Page 6 

will be warm... and that heat will not be accumulating 
inside the scanner!!! 

Some of you more technical types might suggest that a 
regulated power supply is best from which to operate the 
-2004/5/6 or other base scanner. Really, it doesn’t 
matter, though if you already have one available, then by 
all means, use it. The thing is that the built-in power 
supply in the PR0-2004/5/6 is cheap, rated at 12-v/5G0-ma 
which then feeds several regulator circuits. It’s no 
different if you use an external supply, which will also 
feed the internal regulator circuits. So you can drive 
your PR0-2004/5/6 with most anything between 10-16 vDC so 
long as it can produce upwards of a half -amp (500-ma) or 
so. There is only one circuit in the PR0-2004/5/6 which 
operates on an unregulated voltage, and that is the audio 
power amplifier chip, IC-7, which runs straight off the 
12-v supply line. IC-7 is capable of operation over a 
rather wide range of at least 3 to 16 volts, so it is not 

What If Your Base Scanner Doesn't Have A DC Jack? 

Why not install one? Chances are that the mfgr left it 
out to save a buck. Most modern scanners can be readily 
converted to work with external 12-vDC if they don’t 
already come that way. You 1 11 need a drill, a bit of 
wire and a jack of choice. An RCA Phone jack will be just 
fine and is easy to install and connect. You can also 
a standard coaxial power jack such as Radio Shack ? s If 
,-1563 or similar. I 1 11 leave that up to you. The 
main thing you need to know is about the wiring of the 
jack. Its shell or the part that contacts the scanner’s 
metal chassis will be (-) while the center or hot lug 
will be (+)• Now you know the hard part. 

Chances are that the scanner has an internal 12-v power 
supply which is hard-wired to the 110 VAC cable. The low 
voltage DC output of the internal power supply will run 


pretty much straight to the ON-OFF Switch, and that’s 
where you’ll want to pay attention with a voltmeter. 
Connect the (-) lead of the voltmeter to the scanner’s 
metal chassis or a PCB ground trace. Use the (+) lead of 
the meter to measure as described below. One side of the 
On-Off switch will have full time +12v, give or take a 
couple of volts regardless of whether or not the switch 
is ON. (+10 to +16 vDC will be fine.) Now the other side 
of the switch is where you’ll verify with the voltmeter 
that is turned ON or OFF with the switch. When you find 
that spot, solder a wire to the unswitched lug. Solder 
the other end of that wire to the center or hot lug of 
the new power jack discussed above. Bingo! You’re done! 
Now your scanner can go mobile if you like or it can be 
operated on the base (much cooler) with an external AC-DC 
Adaptor as discussed in the preceding section of this 
article. A word of caution: don’t leave the A/C cord 
plugged into the wall if you’re using external DC power. 
Your new DC Power Plug probably won’t be switched like 
that discussed for the PR0-2Q04, 2005 & 2006. 

NOTE: It is possible, though not probable, that some base 
scanners will use an internal power supply radically 
different from 12-volts. If yours is such, sorry this 
article isn’t for you. That’s why you need to make a 
couple of basic checks with a voltmeter first. If the 
switched voltage that you encounter is between 10 and 16 
volts, then you’re in good shape; a 12-v external AC-DC 
Adaptor or automotive 12-volts will power your scanner. 


Ever since the PR0-2005 came out and then the 2006, I 
have been saying that they’re all the same radio. Well, 
they are, but there are small differences from one to the 
next. Last issue, we showed you how to implement the 
PR0-2006 ’s nifty Squelch Hysteresis switch into your 
PRQ-2004, 2005 and maybe other scanners. We all know 
about the different CPU in each of the three, and how the 
2006 ’s runs much faster than the 2004/5. There are two 

1991 VIN5 - Page 7 








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RADIO INTERESTS? (Put YEARS OF EXPERIENCE in each block that applies) 
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Scanning? Radio? Radio? Listening? Radio? 

SCAHHER HOB HHBBK, M-2: $17.95 ♦ $3.08 S&H* 

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0-; -cupaticn: 

Use the below space to tell us anything else you want! 
Enclose a §1$ S.4.S.E, and one loose extra stasp if you 

List the sake 1 aodel of your scanners and other radio equipaer.t: 

List the make & lode! of any computer equipment you own/operate: 

need other information or a personal reply/ 

other differences that I want to tell you about now* 

First, did you know there are two different versions of 
the PR0-2004 ’s CPU? Early models came with a CPU marked 
GR-327 while later ones are GR-0327A. The earlier 327 is 
programmed to switch the 30-KHz Step increment on for the 
old Cellular Phone bands of 825-845 MHz and 870-890 MHz. 
The later 0327A CPU kicks in the 30 KHz Step for the most 
recent cellular bands; 824-849 MHz and 869-894 MHz. To 
find out which you have, program your 2004 for a LIMIT 
SEARCH of 869-894 MHz. If the 30 KHz flag remains on 
throughout either of those bands then yours is the 0327A, 
but if "12.5 KHz" comes on in the 869-870 and 890-894 
ranges, then yours is the 0327. Of course, you can 
always pop the case and look at your CPU. It’s marked on 
the body of the chip. If you have the older chip, you 
can acquire the newer 0327A from Tandy and install it 
yourself. 30 KHz steps for the newer CMT sub-bands is 
the only advantage of the 0327A that I have been able to 
determine. The CPUs in the PR0-2005 and PR0-2Q06 already 
have this update so it’s a factor only in PR0-2004 ’s. 

Now here is another difference between the PR0-2005/6 and 
the PR0-2004. I’ve known about it for some time but have 
forgotten to mention it. There are two extra IF filters 
in the PR0-2005/6 that are not in the PR0-2004. One of 
these is a second 10.7 MHz ceramic IF filter for the lilFM 
section and the other is a narrower 455 KHz ceramic IF 
filter for the AM section! I don’t see a great advantage 
of the extra 10.7 MHz lilFM filter in the PR0-2005/6 but it 
must improve selectivity and spurious rejection somewhat. 
But the addition of the narrow 455 KHz filter in the AM 
section is a definite plus of the PR0-2QQ5/6 over the 
PR0-2004 which has none there. Here’s how you can tell 
the difference. Program your PR0-2004/5/6 ’s with some CB 
channels or do a LIMIT SEARCH of 26.96 MHz to 27.41 MHz. 
When you hear fairly strong signals, stop and check the 
adjacent channels of + and - 10 KHz from the one where 
the signal seems the strongest. In the PR0-2004, chances 
are that you will be able to hear the same signal equally 

well on two or more channels. Here’s an example: say a 
signal is on 27.025 MHz (CB Ch-6). If you can clearly 
hear that same signal on 27.015 and/or 27.035 MHz, then 
yours is a PR0-2Q04! PR0-2005/6 f s won’t hear that signal 

at all or if so, it won’t be as clear. This is due i 
the extra selectivity offered by CF-3 in the PR0-200^ 
lile will offer a nice and easy update mod for PR0-2004 ’s 
and an enhancement for more improvement of PR0-2005/6 ’s 
in a coming issue so stay tuned. 

Now here is the tech issue. All PR0-2004/5/6 scanners 
have the same IF filter for NFM, and it’s bandwidth is 
about 15 KHz, rather wide, but necessary for sloppy NFM 
stations out there on VHF & UHF. In the PR0-2004, the 
output of this filter feeds both the NFM and AM s.ections 
and is the sole determinant of selectivity. In the 
PR0-2005/6, the output of this filter feeds the NFM 
section the same as the PR0-2004, but it also feeds a 
narrower 6 KHz wide filter (CF-3) at the head of the AM 
section. This extra filter makes the AM section more 
selective than the NFM which is righteous and proper! In 
the PR0-2004, the selectivity of the AM and NFM sections 
are about the same, which is not so good when it comes to 
trying to separate the congested CB and Freeband channels 
between 25-28 MHz. It might also be a problem on the VHF 
Aero band in crowded flight areas. Good selectivity has 
always been an elusive goal since radio was invented! 

Now the thing is that you might not ever have noticed the 
deficient selectivity of the AM section in the PR0-2nn4 
because most of your operations may be in the V HF 
bands where NFM is the common mode and where regulatory 
frequency coordination helps minimize adjacent channel 
congestion. Selectivity might not ever have been an issue 
for you, but if you’re a CB’er or compleat scannist, then 
you may have been concerned and this eye-opener can prove 
fruitful later. I have been improving the selectivity of 
receivers of all types and kinds for many years and we 
will concentrate on this area in the issues ahead, not 
only for the PR0-2004/5/6 but for most scanners as well! 

'THE HDHLD SCMEf ! REPORT' (cl 1991 VMS - Page 8 

P0 BOX 262478 
SAN DIEGO , CA 92196-2478 

TURBO-WHOPPER PR0-2006! Shown are the LED Center Tune Meter; 
LED S-Meter; Keyboard Memory Block Controller LEDs, 4-seqDIP 
Switch for misc switch needs; Extended Delay adjust and LED 
Indicator for the Extended Delay. Not shown are many more!